Electronic device, method for controlling electronic device, and electronic device control program

ABSTRACT

An electronic device comprises: a transmitting antenna configured to transmit transmitted waves, a receiving antenna configured to receive reflected waves obtained by reflection of the transmitted waves; and a controller. The controller detects, based on transmitted signals transmitted as the transmitted waves and received signals received as the reflected waves, an object reflecting the transmitted waves. The controller determines frequencies of transmitted waves to be transmitted from the transmitting antenna based on temperature.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to Patent Application No. 2018-176513filed in Japan on Sep. 20, 2018, and Patent Application 2018-179002,filed in Japan on Sep. 25, 2018, and the entire disclosure of theseearlier applications are hereby incorporated for reference.

TECHNICAL FIELD

The present disclosure relates to an electronic device, a method forcontrolling electronic device, and an electronic device control program.

BACKGROUND

For example, in the field of industries related to automobiles, atechnique for measuring distance between an own vehicle and an object isimportant. In particular, in recent years, RADAR (Radio Detecting andRanging) technique for measuring distance between the own vehicle andthe object by transmitting radio waves such as millimeter waves andreceiving reflected waves obtained by reflection by the object such asan obstacle has been studied in various ways. The importance oftechnique for measuring such distances and the like is expected to growmore and more in the future with development of techniques that assistdrivers in driving and related to automated driving that automates apart or all of driving.

Further, various techniques for detecting presence of an object byreceiving reflected waves obtained by reflection of the transmittedradio waves by a predetermined object, have also been proposed. Forexample, PTL 1 discloses an FM-CW radar device emitting transmittedsignals that is linearly FM modulated at a specific cycle toward atarget object, detects a beat signal based on difference between thetransmitted signals, and the received signals from the target object,and measures distance and speed based on frequency analysis of thesesignals.

CITATION LIST Patent Literature

PTL 1: JPH11133144A

SUMMARY

An electronic device according to an embodiment comprises a transmittingantenna configured to transmit transmitted waves, a receiving antennaconfigured to receive reflected waves obtained by reflection of thetransmitted waves, and a controller. The controller detects an objectreflecting the transmitted waves based on transmitted signalstransmitted as the transmitted waves and received signals received asthe reflected waves. The controller determines frequencies oftransmitted waves to be transmitted from the transmitting antenna basedon temperature.

A method for controlling electronic device according to an embodimentincludes the following steps.

(1) A step of transmitting transmitted waves from a transmittingantenna.

(2) A step of receiving reflected waves obtained by reflection of thetransmitted waves from a receiving antenna.

(3) A step of detecting an object reflecting the transmitted waves basedon transmitted signals transmitted as the transmitted waves and receivedsignals received as the reflected waves.

(4) A step of determining frequencies of transmitted waves to betransmitted from the transmitting antenna based on temperature.

An electronic device control program according to an embodiment causes acomputer to perform the steps (1) through (4) described above.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a diagram for explaining a use of an electronic deviceaccording to an embodiment.

FIG. 2 is a functional block diagram schematically showing aconfiguration of an electronic device according to an embodiment.

FIG. 3 is a diagram for explaining a configuration of transmittedsignals according to an embodiment.

FIG. 4 is a functional block diagram schematically showing aconfiguration of a sensor according to an embodiment.

FIG. 5 is a diagram for showing loss of received signals in aconventional sensor.

FIG. 6 is a flowchart for explaining an operation of an electronicdevice according to an embodiment.

FIG. 7 is a diagram for showing an example of intensity of receivedsignals detected for each frequency of transmitted waves in anembodiment.

FIG. 8 is a flowchart for explaining an operation of an electronicdevice according to an embodiment.

FIG. 9 is a flowchart for explaining an operation to associatetemperature with frequency in an electronic device according to anembodiment.

FIG. 10 is a diagram for showing an example of intensity of a receivedsignal detected for each of frequencies of transmitted waves in anembodiment.

FIG. 11 is a diagram for showing another example of intensity of areceived signal detected for each of frequencies of transmitted waves inan embodiment.

FIG. 12 is a diagram for showing an example of association betweentemperature and frequency in an electronic device according to anembodiment.

FIG. 13 is a flowchart for explaining operation of an electronic deviceaccording to an embodiment.

DETAILED DESCRIPTION

It is desirable to improve performance of detection in a technique fordetecting presence of a predetermined object by receiving reflectedwaves obtained by reflection of the transmitted waves by thepredetermined object (object). An objective of the present disclosure isto provide an electronic device, a method for controlling an electronicdevice, and an electronic device control program that can improve theperformance of detecting an object that have reflected the transmittedwaves. According to an embodiment, it is possible to provide anelectronic device, a method for controlling electronic device, and anelectronic device control program that can improve the performance ofdetecting an object that have reflected transmitted waves. Hereinafter,an embodiment will be described in detail with reference to thedrawings.

An electronic device according to an embodiment, for example, by beingmounted on a vehicle such as an automobile (mobile body), can detect thepredetermined object existing around the mobile body. For this reason,an electronic device according to an embodiment can transmit transmittedwaves from a transmitting antenna installed on a mobile body tosurroundings of the mobile body. An electronic device according to anembodiment can receive reflected waves obtained by reflection of thetransmitted waves from the receiving antenna installed on the mobilebody. At least one of the transmitting antenna and the receiving antennamay be provided, for example, in a radar sensor or the like installed inthe mobile body.

Hereinafter, as a typical example, the configuration in which anelectronic device according to an embodiment is mounted in anautomobile, such as a passenger car as an example of a mobile body willbe described. However, mobile bodies on which an electronic deviceaccording to an embodiment is mounted is not limited to the automobile.An electronic device according to an embodiment may be mounted on avariety of mobile bodies, such as buses, trucks, motorcycles, bicycles,ships, aircrafts and drones. Further, mobile bodies on which anelectronic device according to an embodiment is mounted are notnecessarily limited to mobile bodies that move by their own power. Forexample, a mobile body on which an electronic device according to anembodiment is mounted may be a trailer portion towed by a tractor.

First, an example of detecting a body by an electronic device accordingto an embodiment will be described.

FIG. 1 is a diagram for explaining a use of an electronic deviceaccording to an embodiment. FIG. 1 shows an example in which a sensorcomprising a transmitting antenna and a receiving antenna according toan embodiment is installed on a mobile body.

In a mobile body 100 shown in FIG. 1, a sensor 5 comprising atransmitting antenna and a receiving antenna according to an embodimentis installed. Further, the mobile body 100 shown in FIG. 1 shall beequipped with an electronic device 1 according to an embodiment (forexample, built-in). A specific configuration of the electronic device 1will be described below. The sensor 5 may comprise, for example, atleast one of the transmitting antenna and the receiving antenna.Further, the sensor 5 may include at least one of the other functionalparts such as at least a part of a controller 10 included in theelectronic device 1 (FIG. 2), as appropriate. The mobile body 100 shownin FIG. 1 may be an automobile vehicle, such as a passenger car, but maybe an arbitrary type of mobile body. In FIG. 1, the mobile body 100, forexample, may be moving (traveling or slow traveling) in the Y-axispositive direction (traveling direction) shown in FIG. 1, or may bemoving in other directions, or may be stationary without moving.

As shown in FIG. 1, the sensor 5 comprising a plurality of transmittingantennas is installed on a mobile body 100. In the example shown in FIG.1, only one sensor 5 comprising the transmitting antenna and thereceiving antenna is installed in front of the mobile body 100. Here, aposition where the sensor 5 is installed in the mobile body 100 is notlimited to the position shown in FIG. 1, but may be other positions asappropriate. For example, the sensor 5 as shown in FIG. 1 may beinstalled on the left, right, and/or rear of the mobile body 100.Further, a number of such sensors 5 may be an arbitrary number of one ormore, depending on various conditions (or requirements) such as therange and/or accuracy of the measurement in the mobile body 100.

The sensor 5 transmits electromagnetic waves as transmitted waves from atransmitting antenna. For example, if there is a predetermined object(for example, object 200 shown in FIG. 1) around the mobile body 100, atleast a part of the transmitted waves transmitted from the sensor 5 isreflected by the object and becomes reflected waves. Then, by receivingsuch reflected waves by the receiving antenna of the sensor 5 forexample, the electronic device 1 mounted on the mobile body 100 candetect the object.

The sensor 5 comprising a transmitting antenna may typically be a radar(RADAR(Radio Detecting and Ranging) sensor that transmits and receivesradio waves. However, the sensor 5 is not limited to the radar sensor.The sensor 5 according to an embodiment may be a sensor based on atechnique of, for example, LIDAR (Light Detection and Ranging, LaserImaging Detection and Ranging) by light waves. Such sensors can beconfigured to include, for example, a patch antenna. Because techniquessuch as RADAR and LIDAR have been already known, detailed descriptionsmay be simplified or omitted as appropriate.

The electronic device 1 mounted on the mobile body 100 shown in FIG. 1receives reflected waves obtained by reflection of the transmitted wavestransmitted from a transmitting antenna of the sensor 5, from thereceiving antenna. In this way, the electronic device 1 can detect apredetermined object 200 existing within a predetermined distance fromthe mobile body 100. For example, as shown in FIG. 1, the electronicdevice 1 can measure a distance L between the mobile body 100, which isits own vehicle, and the predetermined object 200. Further, theelectronic device 1 can also measure relative speed between the mobilebody 100, which is its own vehicle, and the predetermined object 200.Furthermore, the electronic device 1 can also measure an arrivaldirection (arrival angle θ) in which reflected waves from thepredetermined object 200 arrives at the mobile body 100, which is itsown vehicle.

Here, the object 200 may be at least one of, for example, an oncomingvehicle traveling in a lane adjacent to the mobile body 100, a vehicletraveling in parallel with the mobile body 100, and a vehicle in frontof or behind the mobile body 100 traveling in the same lane as themobile body 100. The object 200 may be an arbitrary body existing aroundthe mobile body 100, such as motorcycles, bicycles, strollers,pedestrians, guardrails, medians, road signs, sidewalk steps, walls, andobstacles. Furthermore, the object 200 may be moving or stopped. Forexample, the object 200 may be an automobile parked or stopped aroundthe mobile body 100. In the present disclosure, objects detected by thesensor 5 include inanimate objects as well as organisms such as humansor animals. The objects detected by the sensors 5 according to thepresent disclosure include markers, in which humans, objects and animalsare included, detected by radar technique.

In FIG. 1, a ratio of the size of the sensor 5 to the size of the mobilebody 100 does not necessarily represent an actual ratio. Further, inFIG. 1, the sensor 5 shows a state of being installed outside the mobilebody 100. However, in an embodiment, the sensor 5 may be installed invarious positions on the mobile body 100. For example, in an embodiment,the sensor 5 may be installed inside the bumper of the mobile body 100so that it does not appear in the outer appearance of the mobile body100. Further, the position where the sensor 5 is installed on the mobilebody 100 may be either outside or inside the mobile body 100. An insidethe mobile body 100 may be, for example, an inside a body of the mobilebody 100, an inside of bumpers, an inside of headlights, an inside ofspace of the vehicle or any combination of these.

Hereinafter, as a typical example, the transmitting antenna of thesensor 5 will be described as transmitting radio waves in a frequencyband such as millimeter wave (above 30 GHz) or quasi-millimeter wave(for example, around 20 GHz to 30 GHz). For example, the transmittingantenna of the sensor 5 may transmit radio waves with a frequencybandwidth of 4 GHz, such as 77 GHz to 81 GHz.

FIG. 2 is a functional block diagram schematically showing an example ofa configuration of the electronic device 1 according to an embodiment.Hereinafter, an example of a configuration of the electronic device 1according to an embodiment will be described.

When measuring distance or the like by a millimeter wave radar, afrequency modulated continuous wave radar (hereafter referred to as FMCWradar (Frequency Modulated Continuous Wave radar)) is often used. TheFMCW radar sweeps frequencies of radio waves to be transmitted, andthereby transmitted signals are generated. Therefore, for example, in amillimeter wave FMCW radar that uses radio waves in the 79 GHz frequencyband, the frequency of the radio waves used will have a frequencybandwidth of 4 GHz, for example, such as 77 GHz to 81 GHz. A radar inthe 79 GHz frequency band is characterized by a wider usable frequencybandwidth than other millimeter wave/quasi-millimeter wave radars, suchas those in the 24 GHz, 60 GHz, and 76 GHz frequency bands. Hereinafter,such an embodiment will be described. Further, the FMCW radar used inthe present disclosure may include the FCM (Fast-Chirp Modulation)radar, which transmits chirp signals with a shorter cycle than usual.The signals generated by a signal generator 21 are not limited to FM-CWsignals. The signals generated by the signal generator 21 may be signalsof various methods other than the FM-CW method. The transmitted signalsequence stored in a storage 40 may be different for these variousmethods. For example, in the case of FM-CW radar signals describedabove, signals whose frequency increases and decreases with each timesample may be used. Because known techniques can be appropriatelyapplied to the various methods described above, more detaileddescription thereof will be omitted.

As shown in FIG. 2, an electronic device 1 according to an embodimentconsists of the sensor 5 and an ECU (Electronic Control Unit) 50. TheECU 50 controls various operations of the mobile body 100. The ECU 50may consist of at least one or more ECUs. The electronic device 1according to an embodiment comprises the controller 10. Further, theelectronic device 1 according to an embodiment may appropriately includeother functional parts such as at least one of a transmitter 20,receivers 30A to 30D, and the storage 40. As shown in FIG. 2, theelectronic device 1 may comprise a plurality of receivers, such as thereceivers 30A to 30D. Hereinafter, when the receiver 30A, the receiver30B, the receiver 30C, and the receiver 30D are not distinguished, theyare simply referred to as “receiver 30”.

The controller 10 may comprise a distance FFT processor 11, a speed FFTprocessor 12, an arrival angle estimator 13, an object detector 14 and afrequency selector 15. These functional parts included in the controller10 will be further described below.

The transmitter 20, as shown in FIG. 2, may comprise a signal generator21, a synthesizer 22, a phase controller 23, an amplifier 24, and atransmitting antenna 25.

The receiver 30 may comprise corresponding receiving antennas 31A to31D, as shown in FIG. 2. Hereinafter, when the receiving antenna 31A,the receiving antenna 311B, the receiving antenna 31C and the receivingantenna 31D are not distinguished, they are simply referred to as“receiving antenna 31”. Further, as shown in FIG. 2, a plurality ofreceivers 30 may respectively comprise a LNA 32, a mixer 33, an IF part34, and an AD converter 35. The receivers 30A to 30D may have the sameconfiguration, respectively. In FIG. 2, as a representative example, aconfiguration of only the receiver 30A is schematically shown.

The above-mentioned sensor 5 may comprise, for example, the transmittingantenna 25 and the receiving 1 l antenna 31. The sensor 5 may alsoinclude at least any one of the other functional parts, such as thecontroller 10, as appropriate.

The controller 10 comprised by the electronic device 1 according to anembodiment can control an operation of the entire electronic device 1including an control of each functional part constituting the electronicdevice 1. The controller 10 may include at least one processor, such asa CPU (central processing unit), for example, in order to providecontrol and processing power for performing various functions. Thecontroller 10 may be realized collectively by one processor, by severalprocessors, or by individual processors. The processor may be realizedas a single integrated circuit. An integrated circuit is also referredto as an IC (Integrated Circuit). A processor may be realized as aplurality of communicably connected integrated circuits and discretecircuits. A processor may be realized based on various other knowntechniques. In an embodiment, the controller 10 may be configured, forexample, as a CPU and a program executed on the CPU. The controller 10may appropriately include a memory necessary for an operation of thecontroller 10.

The storage 40 may store programs executed by the controller 10, resultsof process executed by the controller 10 and the like. Further, thestorage 40 may function as a work memory for the controller 10. Thestorage 40 can be configured by, for example, a semiconductor memory, amagnetic disk or the like, but is not limited to these, and can be anarbitrary storage device. Further, for example, the storage 40 may be astorage medium such as a memory card that is inserted in the electronicdevice 1 according to the present embodiment. Further, the storage 40may also be an internal memory of a CPU that is used as the controller10, as described above.

In an embodiment, the storage 40 stores the correspondence between thefrequency of the transmitted wave T to be transmitted from thetransmitting antenna 25 and the temperature. Such correspondence will bedescribed further below.

In the electronic device 1 according to an embodiment, the controller 10can control at least one of the transmitter 20 and the receiver 30. Inthis case, the controller 10 may control at least one of the transmitter20 and the receiver 30 based on various information stored in thestorage 40. Further, in the electronic device 1 according to anembodiment, the controller 10 may instruct the signal generator 21 togenerate signals, or may control the signal generator 21 to generatesignals.

The signal generator 21 generates the signals (transmitted signals) tobe transmitted as transmitted waves T from the transmitting antenna 25under the control of the controller 10. The signal generator 21 mayassign frequencies of transmitted signals, for example based on controlby the controller 10 (frequency selector 15) when generating transmittedsignals. For example, the signal generator 21 generates signals withpredetermined frequencies in a frequency band, such as 77 GHz to 81 GHz,by receiving frequency information from the controller 10. The signalgenerator 21 may be configured to include a functional part such as avoltage controlled oscillator (VCO).

The signal generator 21 may be configured as a hardware including thefunction, for example, may be configured by a microcontroller and thelike, or for example, may be configured as a combination of a processorsuch as a CPU and a program executed by the processor. Each functionalpart described below may also be configured as a hardware including thefunction, or if possible, for example, by a microcontroller and thelike, or for example, as a combination of a processor such as a CPU anda program executed by the processor.

In the electronic device 1 according to an embodiment, the signalgenerator 21 may generate a transmitted signal (transmitted chirpsignal) such as a chirp signal. In particular, the signal generator 21may generate a signal (linear chirp signal) in which a frequency changesperiodically and linearly. For example, the signal generator 21 maygenerate a chirp signal in which a frequency increases periodically andlinearly from 77 GHz to 81 GHz with passage of time. Further, forexample, the signal generator 21 may generate a signal in which afrequency periodically repeats linear increase (up chirp) and decrease(down chirp) from 77 GHz to 81 GHz with passage of time. The signalgenerated by the signal generator 21 may be preset in the controller 10,for example. Further, the signal generated by the signal generator 21may be stored in advance in a storage 40 or the like, for example.Because chirp signals used in technical fields such as radar are known,more detailed description will be simplified or omitted as appropriate.The signal generated by the signal generator 21 is supplied to thesynthesizer 22.

FIG. 3 is a diagram for explaining an example of a chirp signalgenerated by the signal generator 21.

In FIG. 3, the horizontal axis represents the passage of time, and thevertical axis represents the frequency. In the example shown in FIG. 3,the signal generator 21 generates a linear chirp signal in which afrequency changes periodically and linearly. In FIG. 3, each chirpsignal is shown as c1, c2, . . . c8. As shown in FIG. 3, in each chirpsignal, a frequency increases linearly with passage of time.

In an example shown in FIG. 3, eight chirp signals such as c1, c2, . . ., C8 are included to form one subframe. That is, the subframe 1 and thesubframe 2 shown in FIG. 3 are configured to include eight chirp signalssuch as c1, c2, . . . , C8, respectively. Further, in an example shownin FIG. 3, 16 subframes such as subframes 1 to 16 are included to formone frame. That is, one frame consists of 16 subframes respectively,such as frame 1 and frame 2 shown in FIG. 3. Further, as shown in FIG.3, frame interval of predetermined length may be included between theframes.

In FIG. 3, frame 2 and beyond may have a similar configuration. Further,in FIG. 3, frame 3 and beyond may have a similar configuration. In theelectronic device 1 according to an embodiment, the signal generator 21may generate a transmitted signal as an arbitrary number of frames.Also, in FIG. 3, some chirp signals are shown omitted. Thus, arelationship between frequency and time of a transmitted signalgenerated by the signal generator 21 may be stored in the storage 40,for example.

Thus, the electronic device 1 according to an embodiment may transmitthe transmitted signal consisting of subframes including a plurality ofchirp signals. Also, the electronic device 1 according to an embodimentmay transmit a transmitted signal consisting of a frame including apredetermined number of subframes.

Hereinafter, the electronic device 1 will be described as transmittingthe frame structure transmitted signal as shown in FIG. 3. However, theframe structure as shown in FIG. 3 is an example, and a number of chirpsignals included in one subframe is not limited to eight, for example.In an embodiment, the signal generator 21 may generate subframesincluding an arbitrary number of (for example, any plural) chirpsignals. Further, the subframe structure as shown in FIG. 3 is also anexample. For example, a number of subframes included in one frame is notlimited to 16. In an embodiment, the signal generator 21 may generate aframe including an arbitrary number of (for example, any plural)subframes.

Returning to FIG. 2, the synthesizer 22 raises a frequency of the signalgenerated by the signal generator 21 to a frequency in a predeterminedfrequency band. The synthesizer 22 may raise a frequency of the signalgenerated by the signal generator 21 to a frequency selected as afrequency of the transmitted wave T that is transmitted from thetransmitting antenna 25. The frequency to be selected as the frequencyof the transmitted wave T to be transmitted from the transmittingantenna 25 may be set by the controller 10, for example. For example,the frequency to be selected as the frequency of the transmitted wave Tto be transmitted from the transmitting antenna 25 may be the frequencyselected by the frequency selector 15. Further, the frequency selectedas the frequency of the transmitted wave T to be transmitted from thetransmitting antenna 25 may be stored in the storage 40, for example.The signal whose frequency has been raised by the synthesizer 22 issupplied to the phase controller 23 and the mixer 33. When there are aplurality of receivers 30, the signal whose frequency has been raised bythe synthesizer 22 may be supplied to each of the mixer 33 in theplurality of receivers 30.

The phase controller 23 controls a phase of a transmitted signalsupplied by the synthesizer 22. Specifically, the phase controller 23may adjust the phase of the transmitted signal by appropriatelyadvancing or delaying the phase of the signal supplied from thesynthesizer 22 based on control by the controller 10, for example. Inthis case, the phase controller 23 may adjust the phase of eachtransmitted signal based on path difference of each transmitted wave Tto be transmitted from a plurality of transmitting antennas 25. By thephase controller 23 appropriately adjusting the phase of eachtransmitted signal, the transmitted waves T transmitted from theplurality of transmitting antennas 25 intensify each other in apredetermined direction to form a beam (beamforming). In this case, thecorrelation between the beamforming direction, and the phase amount tobe controlled of the transmitted signals respectively transmitted by theplurality of transmitting antennas 25 may be stored in the storage 40,for example. The transmitted signal whose phase is controlled by thephase controller 23 is supplied to the amplifier 24.

The amplifier 24 amplifies the power (electric power) of the transmittedsignal supplied from the phase controller 23, for example, based oncontrol by the controller 10. Because the technique itself foramplifying the power of the transmitted signal is already known, a moredetailed description will be omitted. The amplifier 24 is connected tothe transmitting antenna 25.

The transmitting antenna 25 outputs (transmits) the transmitted signalamplified by the amplifier 24 as the transmitted wave T. Because thetransmitting antenna 25 can be configured in the same manner as thetransmitting antenna used for known radar technique, a more detaileddescription will be omitted.

In this way, the electronic device 1 according to an embodiment cancomprise the transmitting antenna 25 and transmit the transmitted signal(for example, transmitted chirp signal) as the transmitted wave T fromthe transmitting antenna 25. Here, at least one of each functional partcomprising the electronic device 1 may be housed in a single enclosure.Further, in this case, the single enclosure may be constructed so thatit cannot be easily opened. For example, the transmitting antenna 25,the receiving antenna 31, the amplifier 24 are preferably housed in thesingle enclosure, and this enclosure is preferably constructed so thatit cannot be easily opened. Further, here, when the sensor 5 isinstalled on the mobile body 100 such as an automobile, the transmittingantenna 25 may transmit the transmitted wave T to the outside the mobilebody 100 through a cover member such as a radar cover. In this case, theradar cover may be made of a substance that allows electromagnetic wavesto pass through, such as synthetic resin or rubber. This radar cover maybe, for example, a housing of the sensor 5. By covering the transmittingantenna 25 with a member such as the radar cover, risks that thetransmitting antenna 25 is damaged or malfunctions due to contact withexternal objects can be reduced. Further, the radar cover and thehousing may also be referred to as a radome. The cover member such asthe radar cover described above will be described below.

The electronic device 1 shown in FIG. 2 shows an example equipped withone transmitting antennas 25. However, the electronic device 1 accordingto an embodiment may comprise a plurality of transmitting antennas 25.In this case, the electronic device 1 may also comprise a plurality ofphase controllers 23 and amplifiers 24, respectively, corresponding to anumber of the plurality of transmitting antennas 25. The plurality ofphase controllers 23 may then control the phase of the plurality oftransmitted waves, supplied by the synthesizer 22 and transmitted fromthe plurality of transmitting antennas 25, respectively. Further, theplurality of amplifiers 24 may amplify the power of the plurality oftransmitted signals, transmitted from the plurality of transmittingantennas 25, respectively. In this case, the sensor 5 may be configuredto include the plurality of transmitting antennas Thus, when comprisingthe plurality of transmitting antennas 25, the electronic device 1 shownin FIG. 2 may also be configured to include the plurality of functionalparts necessary for transmitting the transmitted wave T from theplurality of transmitting antennas 25, respectively.

The receiving antenna 31 receives the reflected wave R. The reflectedwave R is the one obtained by reflection of the transmitted wave T onthe predetermined object 200. The receiving antenna 31 may be configuredto include a plurality of antennas, such as the receiving antenna 31A tothe receiving antenna 31D. Because the receiving antenna 31 can beconfigured in the same manner as the receiving antenna used for theknown radar technique, a more detailed description will be omitted. Thereceiving antenna 31 is connected to the LNA 32. The received signalbased on the reflected wave R received by the receiving antenna 31 issupplied to the LNA 32.

The electronic device 1 according to an embodiment can receive thereflected wave R obtained by reflection of the transmitted wave T by apredetermined object 200, transmitted as the transmitted signal(transmitted chirp signal) such as a chirp signal, from a plurality ofthe receiving antennas 31. Thus, when the transmitted chirp signal istransmitted as the transmitted wave T, the received signal based on thereceived reflected wave R is referred to as a received chirp signal.That is, the electronic device 1 receives the received signal (forexample, the received chirp signal) as the reflected wave R from thereceiving antenna 31. Here, when the sensor 5 is installed on the mobilebody 100 such as an automobile, the receiving antenna 31 may receive thereflected wave R from outside the mobile body 100 through the covermember such as the radar cover. In this case, the radar cover may bemade of a substance that allows electromagnetic waves to pass through,such as synthetic resin or rubber. This radar cover may be, for example,a housing of the sensor 5. By covering the receiving antenna 31 with amember such as the radar cover, risks that the receiving antenna 31 isdamaged or malfunctions due to contact with external objects can bereduced. Further, the radar cover described above and the housing mayalso be referred to as a radome.

Further, when the receiving antenna 31 is installed near thetransmitting antenna 25, these may be collectively configured to beincluded in one sensor 5. That is, one sensor 5 may include, forexample, at least one transmitting antenna 25 and at least one receivingantenna 31. For example, one sensor 5 may include a plurality oftransmitting antennas 25 and a plurality of receiving antennas 31. Insuch a case, for example, one radar sensor may be covered with a covermember such as one radar cover.

The LNA 32 amplifies the received signal with low noise based on thereflected wave R received by the receiving antenna 31. The LNA 32 may beused as a low noise amplifier (Low Noise Amplifier), and amplifies thereceived signal supplied from the receiving antenna 31 with low noise.The received signal amplified by the LNA 32 is supplied to the mixer 33.

The mixer 33 generates the beat signal by mixing (multiplying) the RFfrequency received signal supplied from the LNA 32 with the transmittedsignal supplied from the synthesizer 22. The beat signal mixed by themixer 33 is supplied to the IF part 34.

The IF part 34 decreases the frequency of the beat signal to anintermediate frequency (IF (Intermediate Frequency) frequency) byperforming frequency conversion on the beat signal supplied from themixer 33. The beat signal whose frequency is decreased by the IF part 34is supplied to the AD converter 35.

The AD converter 35 digitizes the analog beat signal supplied from theIF part 34. The AD converter 35 may be configured by anyanalog-to-digital conversion circuit (Analog to Digital Converter(ADC)). The beat signal digitized by the AD converter 35 is supplied tothe distance FFT processor 11 of the controller 10. When there are aplurality of receivers 30, each beat signal digitized by the pluralityof AD converters 35 may be supplied to the distance FFT processor 11.

The distance FFT processor 11 estimates the distance between the object200 and the mobile body 100 equipped with the electronic device 1, basedon the beat signal supplied from the AD converter 35. The distance FFTprocessor 11 may include, for example, a processor that performs FastFourier transform. In this case, the distance FFT processor 11 mayconsist of an arbitrary circuit or a chip that performs the Fast FourierTransform (Fast Fourier Transform (FFT)) process. The distance FFTprocessor 11 may perform Fourier transforms other than the Fast Fouriertransform.

The distance FFT processor 11 performs FFT process on the beat signaldigitized by the AD converter 35 (hereinafter, appropriately referred toas “distance FFT process”). For example, the distance FFT processor 11may perform the FFT process on the complex signal supplied from the ADconverter 35. The beat signal digitized by the AD converter 35 can berepresented as a time change of signal intensity (electric power). Thedistance FFT processor 11 performs FFT process on such beat signal,whereby it can be expressed as the signal intensity (electric power)corresponding to each frequency. When the peak is equal to or higherthan a predetermined threshold value in the result obtained byperforming the distance FFT process, the distance FFT processor 11 maydetermine that the predetermined object 200 exists at a distancecorresponding to the peak. For example, such as the Constant False AlarmRate (CFAR) detection process, when a peak value above a threshold valueis detected in the average power or amplitude of the disturbance signal,a method to determine that there is an object (reflecting object)reflecting the transmitted wave is known.

Thus, the electronic device 1 according to an embodiment can detect theobject 200 reflecting the transmitted wave T based on the transmittedsignal transmitted as the transmitted wave T and the received signalreceived as the reflected wave R.

The distance FFT processor 11 can estimate the distance to thepredetermined object based on one chirp signal (for example, c1 shown inFIG. 3). That is, the electronic device 1 can measure (estimate) thedistance L shown in FIG. 1 by performing the distance FFT process.Because the technique itself for measuring (estimating) the distance tothe predetermined object by performing FFT process on the beat signal isknown, a more detailed description will be simplified or omitted asappropriate. Results of the distance FFT process performed by thedistance FFT processor 11 (for example, distance information) may besupplied to the speed FFT processor 12. Further, results of the distanceFFT process performed by the distance FFT processor 11 may be suppliedto the object detector 14.

The speed FFT processor 12 estimates relative speed between the mobilebody 100 equipped with the electronic device 1 and the object 200 basedon the beat signal on which the distance FFT process has been performedby the distance FFT processor 11. The speed FFT processor 12 mayinclude, for example, a processor for performing the Fast Fouriertransform. In this case, the speed FFT processor 12 may consist of anarbitrary circuit or a chip, configured to perform the Fast FourierTransform (Fast Fourier Transform (FFT)) process. The speed FFTprocessor 12 may perform Fourier transforms other than the Fast Fouriertransform.

The speed FFT processor 12 further performs the FFT process on the beatsignal on which the distance FFT process has been performed by thedistance FFT processor 11 (hereinafter, appropriately referred to as“speed FFT process”). For example, the speed FFT processor 12 mayperform FFT process on the complex signal supplied from the distance FFTprocessor 11. The speed FFT processor 12 can estimate relative speedwith a predetermined object based on the subframe of the chirp signal(for example, the subframe 1 shown in FIG. 3). When the distance FFTprocess is performed on the beat signal as described above, a pluralityof vectors can be generated. Relative speed with a predetermined objectcan be estimated by obtaining the phase of the peak in the resultobtained by performing the speed FFT process on these plurality ofvectors. That is, the electronic device 1 can measure (estimate)relative speed between the mobile body 100 shown in FIG. 1 and thepredetermined object 200 by performing the speed FFT process. Becausethe technique itself for measuring (estimating) the relative speed withthe predetermined object by performing the speed FFT process on theresult of performing the distance FFT process is known, more detailedexplanations are simplified or omitted as appropriate. The result ofperforming the speed FFT process by the speed FFT processor 12 (forexample, speed information) may be supplied to the arrival angleestimator 13. Further, the result obtained by performing the speed FFTprocess by the speed FFT processor 12 may also be supplied to the objectdetector 14.

The arrival angle estimator 13 estimates the direction in which thereflected wave R arrives from the predetermined object 200 based on theresult obtained by the speed FFT process performed by the speed FFTprocessor 12. The electronic device 1 can estimate the direction inwhich the reflected wave R arrives by receiving the reflected wave Rfrom the plurality of receiving antennas 31. For example, the pluralityof receiving antennas 31 shall be arranged at predetermined intervals.In this case, the transmitted wave T transmitted from the transmittingantenna 25 is reflected by the predetermined object 200 to become thereflected wave R, and each of the plurality of receiving antennas 31arranged at predetermined intervals respectively receives the reflectedwave R. Then, the arrival angle estimator 13 can estimate the directionin which the reflected wave R arrives at the receiving antenna 31 basedon the phase of the reflected wave R respectively received by each ofthe plurality of receiving antennas 31 and the path difference of eachreflected wave R. That is, the electronic device 1 can measure(estimate) the arrival angle θ shown in FIG. 1 based on the resultobtained by performing the speed FFT process.

Various techniques for estimating the direction in which the reflectedwave R arrives based on the result obtained by performing the speed FFTprocess have been proposed. For example, known algorithms for estimatingthe direction in which the reflected wave arrives include MUSIC(Multiple Signal Classification), ESPRIT (Estimation of SignalParameters via Rotational Invariance Technique) and the like. Therefore,more detailed description of known techniques will be simplified oromitted as appropriate. The information of the arrival angle θ (angleinformation) estimated by the arrival angle estimator 13 may be suppliedto the object detector 14.

The object detector 14 detects objects existing in the range in whichthe transmitted wave T is transmitted, based on information suppliedfrom at least one of the distance FFT processor 11, the speed FFTprocessor 12, and the arrival angle estimator 13. The object detector 14may perform object detection by performing a clustering process, forexample, based on the supplied distance information, speed information,and angle information. As an algorithm used for clustering data, forexample, DBSCAN (Density-based spatial clustering of applications withnoise) is known. In the clustering process, for example, the averagepower of the points constituting the detected object may be calculated.The distance information, the speed information, the angle information,and the electric power information of the object detected by the objectdetector 14 may be supplied to the frequency selector 15. Further, thedistance information, the speed information, the angle information, andthe electric power information of the object detected by the objectdetector 14 may be supplied to the ECU 50. In this case, when the mobilebody 100 is an automobile, communication may be performed using acommunication interface such as CAN (Controller Area Network).

The frequency selector 15 selects the frequency of the transmitted waveT to be transmitted from the transmitting antenna 25 of the electronicdevice 1 based on the information supplied from the object detector 14.As described below, the frequency selector 15 may divide a band that canbe used as a frequency band for transmitting the transmitted wave T intoseveral bands, and select a plurality of frequencies for transmittingthe transmitted wave T from the bands. Further, as described below, thefrequency selector 15 may select the frequency that maximizes the signalintensity (for example, electric power) of the signal received as eachof reflected waves R obtained by reflection of the transmitted waves Twith the plurality of frequencies, transmitted as described above. Thefrequency selector 15 may set the frequency selected as described abovein the synthesizer 22. Thereby, the synthesizer 22 can raise thefrequency of the signal generated by the signal generator 21 to thefrequency selected by the frequency selector 15. Further, the frequencyselector 15 may start an operation of selecting a frequency based on thetemperature information detected by the temperature detector 60described below.

In an embodiment, the frequency selector 15 may select the frequency ofthe transmitted wave T to be transmitted from the transmitting antenna25, for example, based on the temperature detected by the temperaturedetector 60. In this case, as described below, the temperature detector60 may detect, for example, the temperature at the cover member coveringthe transmitting antenna 25 and/or the receiving antenna. Further, asdescribed below, when performing an operation of associating thetemperature with the optimum frequency, the frequency selector 15 maysequentially select a plurality of frequencies by changing the frequencyof the transmitted wave T to be transmitted from the transmittingantenna 25. Also, when performing the operation of associating thetemperature with the optimum frequency, the frequency selector 15 mayselect a frequency that maximizes the signal intensity (for example,electric power) of the signal received as each of reflected waves Robtained by reflection of the transmitted waves T transmitted with aplurality of frequencies. Then, when performing the operation ofdetecting the predetermined object 200, the frequency selector 15 mayset the frequency selected as described above in the synthesizer 22.

The ECU 50 equipped with the electronic device 1 according to anembodiment can control an operation of the entire mobile body 100,including control of each functional part comprising the mobile body100. The ECU 50 may include at least one processor, such as a CPU(Central Processing Unit), for example, in order to provide control andprocessing power for performing various functions. The ECU 50 may berealized collectively by one processor, by several processors, or byindividual processors. The processor may be realized as a singleintegrated circuit. An integrated circuit is also referred to as an IC(Integrated Circuit). A processor may be realized as a plurality ofcommunicably connected integrated circuits and discrete circuits. Aprocessor may be realized based on various other known techniques. In anembodiment, the ECU 50 may be configured, for example, as a CPU and aprogram executed on the CPU. ECU 50 may appropriately include the memorynecessary for an operation of the ECU 50. Further, at least a part of afunction of the controller 10 may be a function of the ECU 50, or atleast a part of a function of the ECU 50 may be a function of thecontroller 10.

The temperature detector 60 can detect the temperature of apredetermined portion of the electronic device 1, for example. Thetemperature detector 60 may be any temperature sensor, such as a sensorthat employs a resistance temperature detector or a thermocouple as longas it can detect the temperature. Specific examples of the portion wherethe temperature detector 60 detects the temperature will be describedbelow. The temperature information detected by the temperature detector60 may be supplied to the controller 10. Further, the temperatureinformation detected by the temperature detector 60 may be supplied tothe frequency selector 15 of the controller 10, for example. Asdescribed above, for example, when performing an operation of detectinga predetermined object 200, the frequency selector 15 may select thefrequency based on the temperature information detected by thetemperature detector 60.

The electronic device 1 shown in FIG. 2 comprises one transmittingantennas 25 and four receiving antennas 31. However, the electronicdevice 1 according to an embodiment may comprise a plurality oftransmitting antennas 25. For example, by comprising two transmittingantennas 25 and four receiving antennas 31, the electronic device 1 canbe considered to comprise a virtual antenna array consisting of eightvirtual antennas. In this way, the electronic device 1 may receive thereflected wave R of the 16 subframes shown in FIG. 3 by using, forexample, eight virtual antennas.

Next, the operation of the electronic device 1 according to anembodiment will be described.

As described above, the electronic device 1 according to an embodimentdetects the object 200 reflecting the transmitted wave T based on thetransmitted signal transmitted as the transmitted wave T and thereceived signal received as the reflected wave R In this case, if atleast a part of at least one of the transmitted wave T and the reflectedwave R is covered by a cover member, for example, made of resin, thiscan affect at least one of the transmission of the transmitted wave Tand the reception of the reflected wave R. When the sensor 5constituting the electronic device 1 is mounted on a mobile body 100such as an automobile, the transmitting antenna 25 and the receivingantenna 31 may be protected by covering them with a cover member such asa radar cover. Further, from a design point of view, when the sensor 5is mounted on the mobile body 100, the transmitting antenna 25 and thereceiving antenna 31 may not be exposed but covered with the covermember such as the radar cover.

Hereinafter, the sensor 5 constituting the electronic device 1 accordingto an embodiment will be described as assuming that at least a part ofthe sensor 5 is covered with the cover member. If the sensor 5 iscovered with the cover member, at least one of the transmitted wave Ttransmitted from the transmitting antenna 25 and the reflected wave Rreceived from the receiving antenna 31 is attenuated when passingthrough the cover member, and loss may occur.

FIG. 4 is a diagram schematically showing the configuration of thesensor 5 constituting the electronic device 1 according to anembodiment. As well as FIG. 1, FIG. 4 shows the state of the sensor 5viewed from above. Further, FIG. 4 schematically shows the positionalrelationship between the sensor 5 and the object 200.

As shown in FIG. 4, the sensor 5 comprises the transmitting antenna 25and the receiving antenna 31 described above. Further, the sensor 5comprises a sensor board 6 and a cover member 7. The sensor board 6 hasa sensor board front surface 6 a and a sensor board rear surface 6 b.Further, the cover member 7 has a cover member front surface 7 a and acover member rear surface 7 b. The cover member 7 is not necessarilylimited to a member such as a radar cover or a radome, but may be amember that constitutes at least part of the mobile body 100, forexample.

As shown in FIG. 4, in the sensor 5, the transmitting antenna 25 andreceiving antenna 31 are arranged on the sensor board 6. In particular,in the sensor board 6, the transmitting antenna 25 and the receivingantenna 31 are arranged on the sensor board front surface 6 a In FIG. 4,the transmitting antenna 25 and the receiving antenna 31 are shown asplanarly configured antennas such as a patch antenna. Further, in thesensor 5, the cover member 7 is arranged to cover the transmittingantenna 25 and the receiving antenna 31. In particular, the cover member7 is arranged so as to be separated from the transmitting antenna 25 andthe receiving antenna 31 by a predetermined distance s. The cover member7 may be made of a material such as synthetic resin or rubber. The covermember 7 may be made of a substance that allows electromagnetic waves topass through.

As described above, in an embodiment, the cover member 7 may cover atleast a part of at least one of the transmitting antenna 25 and thereceiving antenna 31. Further, at least a part of the cover member 7 maybe made of resin.

The applicant has confirmed that when the transmitted signal istransmitted as the transmitted wave T in the configuration shown in FIG.4, the intensity (electric power) of the received signal received as thereflected wave R fluctuates depending on the wavelength A. of thetransmitted wave T. Further, in the configuration shown in FIG. 4, theapplicant has confirmed that the intensity (electric power) of thereceived signal, which is received as the reflected wave R, alsofluctuates depending on the distance s from the transmitting antenna 25and the receiving antenna 31 to the cover member 7.

FIG. 5 is a diagram showing a correlation between the distance s fromthe transmitting antenna 25 and the receiving antenna 31 to the covermember 7 and the loss P of the intensity of the received signal receivedas the reflected wave R. In FIG. 5, the horizontal axis represents thedistance s (see FIG. 4) from the transmitting antenna 25 and receivingantenna 31 to the cover member 7. The vertical axis represents the lossP of the intensity of the received signal received as the reflected waveR. As shown in FIG. 5, when the distance s is gradually increased, forexample, the loss P of the intensity of the received signal repeatsincreasing and decreasing accordingly. That is, depending on thearrangement of the transmitting antenna 25, the receiving antenna 31,and the cover member 7, the loss of the received signal caused by theresin or the like constituting the cover member 7 becomes large. As theloss of the received signal increases, the distance at which the object200 can be detected becomes shorter. Further, as shown in FIG. 5, such achange also differs depending on the frequency of the transmitted waveT.

It is conceivable that the fluctuation of the loss P in the intensity ofthe received signal as described above is caused by the fact that thetransmitted wave T and the received wave R are transmitted and receivedthrough the cover member 7 in the configuration shown in FIG. 4.

As shown in FIG. 4, a part of the transmitted wave T transmitted fromthe transmitting antenna 25 passes through the cover member 7 from thetransmitting antenna 25 and directly reaches the object 200, as shown in(1). On the other hand, as shown in FIG. 4, a part of the transmittedwave T transmitted from the transmitting antenna 25 is reflected by thecover member 7 before returning to the transmitting antenna 25 or thesensor board 6, as shown in (3) followed by (2) Then, a part of thetransmitted wave T that returns to the transmitting antenna 25 or thesensor board 6, as shown in (2), passes through the cover member 7 fromthe transmitting antenna 25 to reach the object 200, as shown in (1). Itis assumed that there is also a transmitted wave T that further repeatssuch reflection. Therefore, it is assumed that the transmitted wave Tthat reaches the object 200 is a composite of the transmitted wave Tdescribed above.

Further, as shown in FIG. 4, a part of the reflected wave R reflected bythe object 200 passes through the cover member 7 and directly reachesthe receiving antenna 31 as shown in (4). On the other hand, as shown inFIG. 4, a part of the reflected wave R that has passed through the covermember 7 and reached the receiving antenna 31 bounces back at thereceiving antenna 31 or sensor board 6 and returns to the cover member7, as shown in (4) followed by (5). Then, a part of the reflected wave Rthat has returned to the cover member 7 as shown in (5) is reflected bythe cover member 7 and then reaches the receiving antenna 31 as shown in(6). Further, it is assumed that there is also a reflected wave R thatfurther repeats such reflection. Therefore, the reflected wave Rreceived by the receiving antenna 31 is assumed to be a composite of thereflected waves R described above.

Here, the transmittance at which the transmitted wave T and thereflected wave R pass through the cover member 7 and the reflectance atwhich the transmitted wave T and the reflected wave R are reflected bythe cover member 7 depend on the material of the cover member 7.Further, it is assumed that the cover member 7 expands or contractsdepending on the temperature That is, the thickness of the cover member7 changes depending on the temperature. Further, the transmittance ofthe transmitted wave T and the reflected wave R passed through the covermember 7 and the reflectance of the transmitted wave T and the reflectedwave R reflected by the cover member 7 also depend on the temperature ofthe cover member 7. Therefore, the loss of the intensity of the receivedsignal received by the receiving antenna 31 as the reflected wave Robtained by the reflection of the transmitted wave T transmitted by thetransmitting antenna 25 depends on the temperature of the cover member7.

In an embodiment, the sensor 5 may comprise a temperature detector 60.The temperature detector 60 may be installed on the cover member 7 asshown in FIG. 4. Here, the temperature detector 60 may be installed oneither the cover member front surface 7 a or the cover member rearsurface 7 b. Further, the temperature detector 60 may be installed onboth the cover member front surface 7 a and the cover member rearsurface 7 b. In this case, among the temperatures detected by theplurality of temperature detectors 60, the lowest temperature may beused, the highest temperature may be used, or the average temperaturemay be used. Further, the temperature detector 60 may be installed onthe sensor board front surface 6 a and % or the sensor board rearsurface 6 b. Further, the temperature detector 60 may be installedanywhere inside the sensor 5 to detect the temperature inside the sensor5, or it may be installed anywhere outside the sensor 5 to detect theambient temperature. In the present disclosure, the number oftemperature detectors 60 may be any number of 1 or more.

With the above configuration, the electronic device 1 operates so thatthe loss of the received signal is reduced even if the characteristicsof the cover member 7 change with temperature.

Hereinafter, the operation of the electronic device 1 according to anembodiment will be described.

The electronic device 1 according to an embodiment transmits atransmitted wave T at different frequencies, and detects an object usingthe frequency at which the intensity (electric power) of the receivedsignal, received as a reflected wave R obtained by reflection of thetransmitted wave T, becomes the strongest.

FIG. 6 through 8 are diagrams to illustrate examples of the operation ofthe electronic device 1 according to an embodiment Hereinafter, anexample of the operation of the electronic device 1 according to anembodiment will be described. Hereinafter, the electronic device 1 willbe described as being configured as a millimeter wave FMCW radar.

FIG. 6 is a flowchart explaining the operation of the electronic device1 according to an embodiment. The operation shown in FIG. 6 may bestarted, for example, when the electronic device 1 detects apredetermined object 200 existing around the mobile body 100.

When the operation shown in FIG. 6 starts, the controller 10 of theelectronic device 1 firstly determines the frequency of the transmittedwave T transmitted from the transmitting antenna 25 (step S1).

In an embodiment, the electronic device 1 transmits a plurality oftransmitted waves T at different frequencies. Therefore, beforedetermining the frequency of the transmitted wave T transmitted from thetransmitting antenna in step S1, the controller 10 prepares a pluralityof different frequencies from the frequency band of the transmitted waveT transmitted from the transmitting antenna 25. For example, as shown inFIG. 7, when the frequency band of the transmitted wave T is from 77 GHzto 81 GHz, the controller 10 may divide this frequency band into eightsections of 0.5 GHz each.

FIG. 7 shows an example in which the frequency band of the transmittedwave T (77 GHz to 81 GHz) is divided into eight sections, and the centerfrequency is set in each of the divided eight frequency bands. Forexample, a center frequency of 77.25 GHz is set in the frequency band of77.0 GHz to 77.5 GHz. Further, for example, a center frequency of 77.75GHz is set in the frequency band of 77.5 GHz to 78.0 GHz. Further, forexample, a center frequency of 78.25 GHz is set in the frequency band of78.0 GHz to 78.5 GHz.

In the example shown in FIG. 7, the frequency band from 77 GHz to 81 GHzis divided into eight sections. However, in an embodiment, a frequencyband of any range may be divided into any plurality of bands. Forexample, in the present disclosure, the frequency band of 77 GHz to 81GHz may be divided by any number of frequency bands. For example, in thepresent disclosure, the frequency band of 77 GHz to 81 GHz may bedivided by two frequency bands or by ten frequency bands. Further, eachfrequency band may be at least two equal frequency bands.

In the example shown in FIG. 7, each of the frequency bands of thetransmitted wave T (77 GHz to 81 GHz) is consecutively divided withoutoverlap. However, in an embodiment, each of the bands obtained bydividing the frequency range of the transmitted wave T may containoverlaps, as long as a plurality of transmitted waves T can betransmitted at different frequencies. For example, when dividing thefrequency band (77 to 81 GHz) of the transmitted wave T, each of thebands may be 77.0 to 78.0 GHz (center frequency 77.5 GHz), 77.5 to 78.5GHz (center frequency 78.0 GHz), 78.0 to 79.0 GHz (center frequency 78.5GHz) . . . . . Further, in an embodiment, each of the bands obtained bydividing the frequency band of the transmitted wave T may containdiscontinuous portions. For example, when dividing the frequency band(77 to 81 GHz) of the transmitted wave T, each of the bands may be 77.0to 77.5 GHz (center frequency 77.25 GHz), 78.0 to 78.5 GHz (centerfrequency 78.25 GHz), 79.0 to 79.5 GHz (center frequency 79.25 GHz) . .. . . In the following explanation, as shown in the example in FIG. 7,the frequency band of 77 GHz to 81 GHz is divided equally into eightsections, and each of the divided eight frequency bands is assumed to becontinuous.

In step S1 shown in FIG. 6, the controller 10 determines the frequencyof the transmitted wave T transmitted from the transmitting antenna 25from any one of the frequency bands (corresponding to the centerfrequency) divided as shown in FIG. 7.

FIG. 8 is a flowchart showing the operation of determining the frequencyperformed in step S1 shown in FIG. 6 in more detail. Hereinafter, theoperation of determining the frequency in step S1 will be described inmore detail.

When the operation of step S1 shown in FIG. 6 starts, as shown in FIG.8, the controller 10 determines whether the electronic device 1satisfies a predetermined condition (step S11). Various conditions canbe assumed as the predetermined conditions in the electronic device 1 tobe determined in step S11. In an embodiment, the predetermined conditionmay be, for example, a condition for the temperature detected by thetemperature detector 60.

As an example, the controller 10 may define the normal temperature rangeof the mobile body 100 on which the electronic device 1 is mounted, suchas 10° C. to 28° C. In this case, if the temperature detector 60 detectsa temperature outside the range of 10° C. to 28° C., the controller 10may determine that the predetermined condition is satisfied. Further, asan example, the controller 10 defines a predetermined temperature change(temperature change rate) detected by the temperature detector 60 in aunit time, and when the temperature change rate becomes equal to orhigher than a predetermined value, the controller 10 may determine thatthe predetermined condition is satisfied. That is, in this case, whenthe temperature detector 60 detects a certain temperature change, it isdetermined that the predetermined condition is satisfied. As describedabove, the temperature detector 60 may be installed at an arbitrarylocation inside the sensor 5 to detect the temperature inside the sensor5, or may be installed at an arbitrary location outside the sensor 5 todetect the ambient temperature.

The temperature detector 60 may also be used to detect the temperatureof the cover member 7 at the sensor 5, as shown in FIG. 4. Therefore, asanother example, the controller 10 may define the normal temperaturerange of the cover member 7 as 15° C. to 25° C. In this case, if thetemperature detector 60 detects that the temperature of the cover member7 is outside the range of 15′ C to 25° C., the controller 10 maydetermine that the predetermined condition is satisfied. Further, asanother example, the controller 10 defines a predetermined temperaturechange (temperature change rate) in a unit time of the cover member 7,and when the temperature change rate of the cover member 7 becomes equalto or higher than a predetermined value, it may be determined that thepredetermined condition is satisfied. That is, in this case, when acertain degree of temperature change is detected by the temperaturedetector 60 at the cover member 7, it is determined that thepredetermined condition is satisfied.

Thus, for example, when the temperature detector 60 detects atemperature outside the predetermined range at the cover member 7 or inthe vicinity of the cover member 7, the controller 10 may determine thatthe predetermined condition is satisfied. When the temperature detector60 detects a predetermined temperature change at the cover member 7 orin the vicinity of the cover member 7, the controller 10 may determinethat the predetermined conditions is satisfied. In the presentdisclosure, the controller 10 may determine that a predeterminedcondition is satisfied based on the detected temperature detected by thetemperature detector 60.

If it is determined in step S11 that the predetermined condition is notsatisfied, the controller 10 selects a predetermined frequency (stepS12) and terminates the operation shown in FIG. 8. Here, thepredetermined frequency in step S12 may be, for example, the frequencyspecified by default, or the frequency used in the previous operationmay be used this time as well. That is, in step S12, the frequency maybe determined without performing the operation shown in FIG. 8. Asdescribed above, in an embodiment, when the predetermined condition isnot satisfied in step S11, the controller 10 may select a predeterminedfrequency such as the default frequency or the frequency used in theprevious operation.

On the other hand, when it is determined in step S11 that thepredetermined condition is satisfied, the controller 10 sets the firstfrequency among the frequencies prepared as the frequencies of thetransmitted wave T (step S13). More specifically, in step S13, thefrequency selector 15 notifies the synthesizer 22 of the first frequencyamong the plurality of different frequencies as shown as the centerfrequency in FIG. 7. This allows the synthesizer 22 to set the frequencyof the signal generated by the signal generator 21 to the frequencynotified by the frequency selector 15. Here, the first frequency may,be, for example, the lowest frequency 77.25 GHz shown in the uppermoststage among the plurality of different frequencies as shown as thecenter frequency in FIG. 7.

After the frequency has been set in step S13, the electronic device 1transmits the transmitted wave T at the set frequency from thetransmitting antenna 25 (step S14). As described above, when thetransmitted wave T is transmitted from the transmitting antenna 25 and apredetermined object 200 or the like exists around the mobile body 100,the transmitted wave T is reflected and becomes a reflected wave R.

When the transmitted wave T is transmitted in step S14, the electronicdevice 1 receives the reflected wave R from the receiving antenna 31(step S15). When the reflected wave R is received in step S15, thecontroller 10 stores the signal intensity (for example, electric power)of the received signal received as the reflected wave R in the storage40 (step S16), for example. For example, it is assumed that thetransmitted wave T with a frequency of 77.25 GHz is transmitted in stepS14 and the intensity (electric power) of the received signal receivedas the reflected wave R in step S15 is a [dB] as shown in FIG. 7. Inthis case, in step S16, the controller 10 stores the signal intensity a[dB] in the storage 40 or the like corresponding to the frequency 77.25GHz.

After the signal intensity has been stored in step S16, the controller10 determines whether a next frequency for transmitting the transmittedwave T exists (step S17). If the next frequency exists in step S17, thecontroller 1) sets the next frequency (step S18). For example, in stepS12, it is assumed that the controller 10 sets the center frequency77.25 GHz shown in FIG. 7 as the first frequency. In this case, thecontroller 10 determines in step S17 that 77.75 GHz exists as the nextfrequency, and sets the frequency of 77.75 GHz in step S18.

After the frequency is set in step S18, the controller 10 transmits thetransmitted wave T in step S14 using that frequency as well as afterstep S13, and receives the reflected wave R in step S15. For example, itis assumed that the transmitted wave T with a frequency of 77.75 GHz istransmitted in step S14 and the intensity (electric power) of thereceived signal received as the reflected wave R in step S15 is b [dB]as shown in FIG. 7. In this case, in step S16, the controller 10 storesthe signal intensity b [dB] in the storage 40 or the like correspondingto the frequency 77.75 GHz. Then, the controller 10 determines in stepS17 that the center frequency 78.25 GHz shown in FIG. 7 exists as thenext frequency, and sets 78.25 GHz as the frequency for transmitting thetransmitted wave T in step S18.

In the same way thereafter, the controller 10 repeats step S14 to stepS18 shown in FIG. 8 as long as the rest of the center frequency shown inFIG. 7 exists. Then, it is assumed that the controller 10 sets 80.75 GHzshown in FIG. 7 as the frequency for transmitting the transmitted wave Tin step S18. In this case, the controller 10 transmits the transmittedwave T in step S14, receives the reflected wave R in step S15, storesthe signal intensity in step S16, and then determines that there is nonext frequency in step S17.

If it is determined in step S17 that there is no next frequency, thetable shown in FIG. 7 will be stored in the storage 40. That is, whenproceeding to NO in step S17, as shown in FIG. 7, the values of thesignal intensities a to h [dB] corresponding to the respectivefrequencies at the center frequency of 77.25 to 80.75 GHz are stored,respectively.

When proceeding to NO in step S17, the controller 10 selects thefrequency at which the signal intensity (electric power) is maximized(step S19). For example, it is assumed that the value e [dB] is themaximum value among the values of the signal intensities a to h [dB]shown in FIG. 7. In this case, the controller 10 selects the frequency78.75 GHz corresponding to the value e [dB] in step S19. When thefrequency is selected in step S19, the controller 10 terminates theoperation shown in FIG. 8 and determines the selected frequency as thefrequency for transmitting the transmitted wave T.

In the above description, the controller 10 sets the lowest frequency(77.25 GHz) as the first frequency among the center frequencies shown inFIG. 7, and the frequency to be set next is gradually increased.However, in an embodiment, the frequency may be set in other ways. Forexample, the controller 10 may set the maximum frequency (80.75 GHz) asthe first frequency among the center frequencies shown in FIG. 7, andthe frequency to be set next may be gradually reduced. Further, thefrequency to be selected as the first frequency does not have to be themaximum or the minimum among the prepared frequency band. Further, thefrequency to be set next does not have to be changed to graduallyincrease or decrease.

Thus, in the electronic device 1 according to an embodiment, thecontroller 10 receives from the receiving antenna 31 each reflected waveR obtained by reflection of a plurality of transmitted waves T withdifferent frequencies transmitted from the transmitting antenna 25.Then, the controller 10 determines the frequency of the transmitted waveT to be transmitted from the transmitting antenna 25 based on theresults received from the receiving antenna 31.

Here, the controller 10 may sequentially transmit a plurality oftransmitted waves from the transmitting antenna 25, and receive each ofthe reflected waves obtained by reflection of the plurality oftransmitted waves from the receiving antenna 31. Further, the controller10 may determine the frequency of the transmitted wave transmitted fromthe transmitting antenna 25 based on the intensity of the receivedsignal received as each of reflected waves obtained by reflection of theplurality of transmitted waves. More specifically, the controller 10 maydetermine the frequency of the transmitted wave with the highestintensity of the received signal received as the reflected wave amongthe plurality of transmitted waves to be the frequency of thetransmitted wave to be transmitted from the transmitting antenna 25.

As described above, in an embodiment, the controller 10 may start anoperation of determining the frequency of the transmitted wave T when apredetermined condition is satisfied. In an embodiment, the controller10 may start the operation of determining the frequency of thetransmitted wave T when the electronic device 1 is started or activated.Further, in an embodiment, when the controller 10 detects a temperatureout of the predetermined range, the controller 10 may start an operationof determining the frequency of the transmitted wave T. Further, in anembodiment, when detecting a predetermined temperature change, thecontroller 10 may start an operation of determining the frequency of thetransmitted wave T.

Further, in an embodiment, when detecting a temperature out of thepredetermined range at the cover member 7 or in the vicinity of thecover member 7, the controller 10 may start an operation of determiningthe frequency of the transmitted wave T. Further, in an embodiment, whendetecting a predetermined temperature change at the cover member 7 or inthe vicinity of the cover member 7, the controller 10 may start anoperation of determining the frequency of the transmitted wave T.

Returning to FIG. 6, when the frequency of the transmitted wave T isdetermined in step S1, the controller 10 controls the transmittingantenna 25 of the transmitter 20 to transmit the chirp signal as thetransmitted wave T with the determined frequency (Step S2).Specifically, the controller 10 instructs the signal generator 21 togenerate a transmitted signal (chirp signal). The controller 10 thencontrols the chirp signal to be transmitted as a transmitted wave T fromthe transmitting antenna 25 through the synthesizer 22, the phasecontroller 23, and the amplifier 24. Here, the frequency selector 15 ofthe controller 10 notifies the synthesizer 22 of the frequencydetermined in step S1. Then, the synthesizer 22 raises the frequency ofthe signal generated by the signal generator 21 to the frequencynotified by the frequency selector 15.

When a transmitted signal is transmitted as a transmitted wave T in stepS2, for example, when a predetermined object 200 exists around themobile body 100, the transmitted wave T is reflected by the object 200and becomes a reflected wave R.

When the chirp signal is transmitted in step S2, the controller 10controls the receiving antenna 31 of the receiver 30 to receive thechirp signal as the reflected wave R (step S3). When the chirp signal isreceived in step S3, the controller 10 controls the receiver 30 togenerate a beat signal by multiplying the transmitted chirp signal andthe received chirp signal (step S4). Specifically, the controller 10controls the chirp signal received from the receiving antenna 31 to beamplified by the LNA 32 and multiplied with the transmitted chirp signalby the mixer 33. The process from step S1 to step S3 may be performed,for example, by employing a known millimeter wave FMCW radar technique.

When the beat signal is generated in step S4, the controller 10estimates the distance L to the predetermined object 200 based on eachgenerated chirp signal (step S5).

In step S5, the distance FFT processor 11 performs distance FFT processon the beat signal generated in step S4. When the distance FFT processis performed in step S5, the signal intensity (electric power)corresponding to each frequency is obtained. In step S5, the distanceFFT processor 11 may perform distance FFT process on the digital beatsignal supplied from the AD converter 35. In step S5, the distance FFTprocessor 11 may estimate the distance to the predetermined object 200based on determining whether among the generated beat signal, the peakin the result obtained by performing the distance FFT process is equalto or higher than a predetermined threshold value. Further, the beatsignal on which the distance FFT process is performed in step S5 may bea unit of one chirp signal (for example, c1 shown in FIG. 3), forexample.

After the distance is estimated in step S5, the controller 10 estimatesthe relative speed with the object 200 (step S6).

In step S6, the speed FFT processor 12 performs speed FFT process on theresult on which the distance FFT process has been performed in step S5.In step S6, the speed FFT processor 12 may perform the speed FFT processon the result on which the distance FFT process has been performed bythe distance FFT processor 11. In step S6, the speed FFT processor 12may estimate the relative speed with the predetermined object 200 basedon determining whether the peak in the result obtained by performing thespeed FFT process is equal to or higher than a predetermined thresholdvalue. The signal on which the speed FFT process is performed in step S6may be a unit of chirp signals (for example, c1 to c8 shown in FIG. 3)included in one subframe, for example.

After the distance is estimated in step S6, the controller 10 estimatesthe direction in which the reflected wave R arrives from the object 200(step S7).

In step S7, the arrival angle estimator 13 may estimate the direction inwhich the reflected wave R arrives from the object 200 based on theresult obtained by performing the speed FFT process in step S6. In stepS7, the arrival angle estimator 13 may estimate the direction in whichthe reflected wave R arrives by using an algorithm such as MUSIC andESPRIT as described above. The signal in which the arrival direction isestimated in step S7 may, for example, be a unit of all of the chirpsignals in 16 subframes (subframe 1 to subframe 16 shown in FIG. 3)included in one frame (for example, frame 1 shown in FIG. 3).

When the arrival direction is estimated in step S7, the controller 10detects the object 200 (step S8). In step S8, the object detector 14 maydetermine whether a predetermined object 200 exists based on at leastone of the distance estimated in step S5, the relative speed estimatedin step S6, and the arrival direction estimated in step 7. Theelectronic device 1 according to an embodiment may perform the operationshown in FIG. 6 for each frame, for example.

The radar sensors using conventional millimeter wave radar technique areexpected to be unable to perform good measurements depending on thepositional relationship with the transmitting antennas and/or thereceiving antennas when the cover member such as the radar cover is madeof resin, for example. For example, the transmitted signal and/or thereceived signal may pass through the cover member made of resin, whichmay cause a loss in the intensity of the received signal. If the loss ofthe intensity of the received signal becomes large, it is assumed thatthe distance that the radar sensor can detect a predetermined objectbecomes shorter. This is mainly due to the fact that the resin thatmakes up the cover member expands or contracts depending on thetemperature, which changes the loss of intensity of the received signalwhen the transmitted signal and/or the received signal pass through theresin.

On the other hand, the electronic device 1 according to an embodimentmeasures the temperature at the cover member 7 or the ambienttemperature, and the like, and operates to optimize the frequency of thetransmitted wave T when the temperature is out of a predetermined range.In this case, the electronic device 1 divides the bands that can be usedas the frequency of the transmitted wave T (see FIG. 7), and transmitsthe transmitted wave T at the frequency in each divided band. Theelectronic device 1 then determines the frequency at which the powerintensity of the received signal received as the reflected wave R,obtained by reflection of the transmitted wave T, is maximized, to bethe frequency of the transmitted wave T.

As a result, the electronic device 1 can determine the optimum frequencyfor the transmitted wave T even when the temperature at the cover member7 or the ambient temperature changes to a considerable extent. In thisway, because the electronic device 1 can minimize the loss of theintensity of the received signal caused by the resin constituting thecover member 7, the distance at which a predetermined object can bedetected can be maximized.

Therefore, according to an embodiment of the electronic device 1, theperformance of detecting objects reflecting the transmitted waves can beimproved.

FIGS. 9 to 13 are diagrams for explaining another example of theoperation of the electronic device 1 according to an embodimentHereinafter, another example of the operation of the electronic device 1according to an embodiment will be described. Hereinafter, as in thecase described above, the electronic device 1 will be described as beingconfigured as a millimeter wave type FMCW radar.

Firstly, in the electronic device 1 according to an embodiment, theoperation of associating the temperature with the optimum frequency willbe described. The electronic device 1 according to an embodiment, at apredetermined temperature, transmits the transmitted wave T at adifferent frequency, and associates, for example, a frequency (optimalfrequency) at which the intensity (electric power) of the receivedsignal received as the reflected wave R obtained by reflection of thetransmitted wave T becomes the strongest, with the predeterminedtemperature.

FIG. 9 is a flowchart for showing an operation of associating thetemperature with the optimum frequency (hereinafter, appropriatelyreferred to as “association”) in the electronic device 1 according to anembodiment. The association shown in FIG. 9 may be, for example, theoperation to be performed at the time of factory shipment of the mobilebody 100 equipped with the electronic device 1 (sensor 5). Theassociation shown in FIG. 9 can also be used as a calibration, forexample, to be performed as a test mode, in a mobile body 100 equippedwith the electronic device 1 (sensor 5).

In the association shown in FIG. 9, the electronic device 1 is operatedat a predetermined temperature at the cover member 7 or in the vicinityof the cover member 7. Therefore, when making this association, anytemperature control mechanism, such as a heater and/or cooler, is usedto allow the cover member 7 or the vicinity of the cover member 7 toreach a predetermined temperature, for example. Such a temperaturecontrol mechanism may be installed inside the sensor 5, for example, ormay be installed outside the sensor 5 such as a temperature controllabletest environment.

The association shown in FIG. 9 is performed for a predeterminedtemperature range. Further, in an embodiment, the predeterminedtemperature range may be a plurality of temperature ranges. Therefore,in this case, the association shown in FIG. 9 may be performed for eachof the plurality of predetermined temperature ranges Here, variousranges can be assumed as the predetermined temperature range. Forexample, the predetermined temperature range may be in increments of 20°C. such as 0° C. to 20° C., 200° C. to 40° C., 40° C. to 60° C., and thelike. Further, the predetermined temperature range may be in incrementsof 10° C., such as 0° C. to 10° C., 10° C. to 20° C. 20° C. to 30° C.,and the like. Further, the predetermined temperature range may be inincrements of 5° C. such as 0° C. to 5° C., 5° C. to 10° C., 10° C. to15° C., and the like. Further, the predetermined temperature range maybe in increments of 1° C., such as 0° C. to 1° C. 1° C. to 2° C., 2° C.to 3° C., and the like. As described above, the predeterminedtemperature range may be in any temperature increment, in anytemperature range. In addition, in this disclosure, the description ofA° C. to B° C. and the temperature range A to B [° C.] with A and B asarbitrary numbers shall mean A° C. or higher and lower than B° C.

Hereinafter, the predetermined temperature range will be described as,for an example, a temperature range of −40° C. to 100° C. in incrementsof 20° C. That is, in this case, the association shown in FIG. 9 may beperformed (that is, multiple times) for each of the followingtemperature ranges: −40° C. to −20° C. −20° C. to 0° C., 0° C. to 20° C.20° C. to 40° C., 40° C. to 60° C., 60° C. to 80° C., and 80° C. to 100°C.

As an example, firstly, the association performed for a predeterminedtemperature range of 0° C. to 20° C. will be described. When theoperation shown in FIG. 9 starts, the controller 10 determines whetherthe temperature detected by the temperature detector 60 is within thepredetermined temperature range of 0° C. to 20° C. (step S21). Thetemperature detected by the temperature detector 60 in step S21 may bethe temperature at the cover member 7 or in the vicinity of the covermember 7. That is, in step S21, it is determined whether the temperatureat the cover member 7 or in the vicinity of the cover member 7 is within0° C. to 20° C.

If it is determined that the temperature is not within the predeterminedrange in step S21, the controller 10 terminates the operation shown inFIG. 9. When the operation shown in FIG. 9 is terminated in this way,the controller 10 may wait until the temperature detected by thetemperature detector 60 reaches the predetermined temperature range bystarting the operation shown in FIG. 9 again. For example, if thetemperature detected by the temperature detector 60 is 23° C. whenassociating with the predetermined temperature range of 0° C. to 20° C.as described above, the cover member 7 or the vicinity of the covermember 7 may be cooled by using a temperature control mechanism such asa cooler. By doing so, it is assumed that over time the temperaturedetected by the temperature detector 60 will change to fall within apredetermined temperature range (0° C. to 20° C.) Further, for example,if the temperature detected by the temperature detector 60 is −5° C.when associating with the predetermined temperature range of 0° C. to20° C. as described above, the cover member 7 or the vicinity of thecover member 7 may be heated using a temperature control mechanism suchas a heater. By doing so, it is assumed that over time the temperaturedetected by the temperature detector 60 will change to fall within apredetermined temperature range (0° C. to 20° C.).

If the operation shown in FIG. 9 is terminated when it is determinedthat the temperature is not within the predetermined temperature range(NO) in step S21, the controller 10 may change the predeterminedtemperature range for the association. For example, if the temperaturedetected by the temperature detector 60 is 230° C. when associating withthe predetermined temperature range of 0° C. to 20° C. as describedabove, the controller 10 may change the predetermined temperature rangefor the association to 20° C. to 40° C. By doing so, by starting theoperation shown in FIG. 9 again, it is determined that the temperaturedetected by the temperature detector 60 is within the predeterminedtemperature range.

On the other hand, when it is determined in step S21 that thetemperature is within the predetermined temperature range, thecontroller 10 sets the first frequency among the frequencies preparedfor the frequency of the transmitted wave T (step S22).

Here, the frequency to be set when the electronic device 1 transmits thetransmitted wave T will be described. In an embodiment, the electronicdevice 1 transmits a plurality of transmitted waves T at differentfrequencies. Therefore, before determining the frequency of thetransmitted wave T to be transmitted from the transmitting antenna 25 instep S22, the controller 10 prepares a plurality of differentfrequencies from the frequency band of the transmitted wave T to betransmitted from the transmitting antenna 25. For example, when thefrequency band of the transmitted wave T is from 77 GHz to 81 GHz, asshown in FIG. 10, the controller 10 may divide this frequency band intoeight sections of 0.5 GHz each.

FIG. 10 shows an example in which the frequency band (77 GHz to 81 GHz)of the transmitted wave T is divided into eight sections, and the centerfrequency is set for each of the eight divided frequency bands. Forexample, a center frequency of 77.25 GHz is set for the frequency bandof 77.0 GHz to 77.5 GHz. Further, for example, a center frequency of77.75 GHz is set for the frequency band of 77.5 GHz to 78.0 GHz.Further, for example, a center frequency of 78.25 GHz is set for thefrequency band of 78.0 GHz to 78.5 GHz. In addition, in this disclosure,the description of A° C. to B° C. and the temperature range A to B [°C.] with A and B as arbitrary numbers shall mean A° C. or higher andlower than B° C.

In the example shown in FIG. 10, the frequency band from 77 GHz to 81GHz is divided into eight sections. However, in an embodiment, afrequency band of any range may be divided into any plurality of bands.

Further, in the example shown in FIG. 10, each of the bands obtained bydividing the frequency range of the transmitted wave T (77 GHz to 81GHz) is consecutively divided without overlap. However, in anembodiment, each of the bands obtained by dividing the frequency rangeof the transmitted wave T may contain overlaps, as long as a pluralityof transmitted waves T can be transmitted at different frequencies. Forexample, when dividing the frequency band (77 to 81 GHz) of thetransmitted wave T, each of the bands may be 77.0 to 78.0 GHz (centerfrequency 77.5 GHz), 77.5 to 78.5 GHz (center frequency 78.0 GHz), 78.0to 79.0 GHz (center frequency 78.5 GHz) . . . . . Further, in anembodiment, each of the bands obtained by dividing the frequency band ofthe transmitted wave T may contain discontinuous portions. For example,when dividing the frequency band (77 to 81 GHz) of the transmitted waveT, each of the bands may be 77.0 to 77.5 GHz (center frequency 77.25GHz), 78.0 to 78.5 GHz (center frequency 78.25 GHz), 79.0 to 79.5 GHz(center frequency 79.25 GHz), . . . . In the following explanation, asshown in the example in FIG. 10, the frequency band of 77 GHz to 81 GHzis divided equally into eight sections, and each of the divided eightfrequency bands is assumed to be continuous.

In step S22 shown in FIG. 9, the controller 10 sets the frequency of thetransmitted wave T to be transmitted from the transmitting antenna 25from any one of the frequency bands (corresponding to the centerfrequency) divided as shown in FIG. 10. More specifically, in step S22,the frequency selector 15 notifies the synthesizer 22 of the firstfrequency among the plurality of different frequencies as shown as thecenter frequency in FIG. 10. This allows the synthesizer 22 to set thefrequency of the signal generated by the signal generator 21 to thefrequency notified by the frequency selector 15. Here, the firstfrequency may be, for example, the lowest frequency 77.25 GHz shown inthe uppermost stage among the plurality of different frequencies shownas the center frequency in FIG. 10.

After the frequency has been set in step S22, the electronic device 1transmits the transmitted wave T at the set frequency from thetransmitting antenna 25 (step S23). As described above, when thetransmitted wave T is transmitted from the transmitting antenna 25 and apredetermined object 200 or the like exists around the mobile body 100,the transmitted wave T is reflected and becomes a reflected wave R.

When the transmitted wave T is transmitted in step S23, the electronicdevice 1 receives the reflected wave R from the receiving antenna 31(step S24). When the reflected wave R is received in step S24, thecontroller 10 stores the signal intensity (for example, electric power)of the received signal received as the reflected wave R in the storage40, for example (step S25). By the time of process in step S25, thecontroller 10 may detect the predetermined object 200 by performing theFast Fourier Transform process on the beat signal generated bymultiplying the transmitted signal and the received signal to calculatethe distance, speed, angle, and electric power. The controller 10 maystore the electric power calculated in this way in the storage 40. Suchobject detection will be further described below. For example, it isassumed that the transmitted wave T with a frequency of 77.25 GHz istransmitted in step S23 and the intensity (electric power) of thereceived signal received as the reflected wave R in step S24 is a1 [dB]as shown in FIG. 10. In this case, in step S25, the controller 10 storesthe signal intensity a1 [dB] in the storage 40 or the like inassociation with the frequency 77.25 GHz.

After the signal intensity has been stored in step S25, the controller10 determines whether a next frequency for transmitting the transmittedwave T exists (step S26). If the next frequency exists in step S26, thecontroller 10 sets the next frequency (step S27). For example, in stepS22, it is assumed that the controller 10 sets the center frequency77.25 GHz shown in FIG. 10 as the first frequency. In this case, thecontroller 10 determines in step S26 that 77.75 GHz exists as the nextfrequency, and sets the frequency of 77.75 GHz in step S27.

After the frequency is set in step S27, the controller 10 transmits thetransmitted wave T in step S23 using that frequency as well as afterstep S22, and receives the reflected wave R in step S24. For example, itis assumed that the transmitted wave T with a frequency of 77.75 GHz istransmitted in step S23 and the intensity (electric power) of thereceived signal received as the reflected wave R in step S24 is b1 [dB]as shown in FIG. 10. In this case, in step S25, the controller 10 storesthe signal intensity b1 [dB] in the storage 40 or the like correspondingto the frequency 77.75 GHz. Then, the controller 10 determines in stepS26 that the center frequency 78.25 GHz shown in FIG. 10 exists as thenext frequency, and sets 78.25 GHz as the frequency for transmitting thetransmitted wave T in step S27.

In the same way thereafter, the controller 10 repeats step S23 to stepS27 shown in FIG. 9 as long as the rest of the center frequency shown inFIG. 10 exists. Then, it is assumed that the controller 10 sets 80.75GHz shown in FIG. 10 as the frequency for transmitting the transmittedwave T in step S27. In this case, the controller 10 transmits thetransmitted wave T in step S23, receives the reflected wave R in stepS24, stores the signal intensity in step S25, and then determines thatthere is no next frequency in step S26.

If it is determined in step S26 that there is no next frequency, thetable shown in FIG. 10 will be stored in the storage 40. That is, whenproceeding to NO in step S26, as shown in FIG. 10, the values of thesignal intensities a1 to h1 [dB] corresponding to the respectivefrequencies at the center frequency of 77.25 to 80.75 GHz are stored forthe temperature range 0° C. to 20° C., respectively.

When proceeding to NO in step S26, the controller 10 associates thefrequency at which the signal intensity (electric power) is maximizedwith the predetermined temperature range described above (step S28) Thatis, in this example, the correspondence was performed with apredetermined temperature range of 0° C. to 20° C. For example, it isassumed that the value f1 [dB] is the maximum among the values of thesignal intensities a1 to h1 [dB] shown in FIG. 10. In this case, in stepS28, the controller 10 associates the frequency 79.75 GHz correspondingto the value f1 [dB] with the temperature range of 0° C. to 20° C.(stores in the storage 40). When the frequency is associated with thetemperature in step S28, the controller 10 terminates the operationshown in FIG. 9. In this way, the electronic device 1 can perform theassociation for the temperature range of 0° C. to 20° C. In the aboveexample, the electronic device 1 associates a frequency of 79.75 GHz asthe optimum frequency with the temperature range of 0° C. to 20° C.

In the above description, the controller 10 sets the lowest frequency(77.25 GHz) as the first frequency among the center frequencies shown inFIG. 10, and the frequency to be set next is gradually increased.However, in an embodiment, the frequency may be set in other ways. Forexample, the controller 10 may set the maximum frequency (80.75 GHz) asthe first frequency among the center frequencies shown in FIG. 10, andthe frequency to be set next may be gradually reduced. Further, thefrequency to be selected as the first frequency does not have to be themaximum or the minimum among the prepared frequency band. Further, thefrequency to be set next does not have to be changed to graduallyincrease or decrease.

As described above, after the association shown in FIG. 9 is performedfor the temperature range of 0° C. to 20° C., the controller 10 againperforms the association shown in FIG. 9 for the next predeterminedtemperature range. Hereinafter, an example in which the association forthe next predetermined temperature range of 20° C. to 40° C. isperformed, following the temperature range of 0° C. to 20° C., will beshown.

FIG. 11 is a diagram for showing an example of the results of performingthe association shown in FIG. 9 for the temperature range of 20° C. to40° C. FIG. 11 is a diagram for showing the results of performing theassociation shown in FIG. 9 for the predetermined temperature range of200° C. to 40° C. in the same manner as the results shown in FIG. 10.That is. FIG. 11 shows an example in which the values of the signalintensity a2 to h2 [dB] corresponding to the respective frequencies atthe center frequency of 77.25 to 80.75 GHz are stored for thetemperature range of 20° C. to 40° C., respectively. For example, it isassumed that the value b2 [dB] is the highest among the values of thesignal intensities a2 to h2 [dB] shown in FIG. 11. In this case, in stepS28 (FIG. 9), the controller 10 associates the frequency 77.75 GHzcorresponding to the value b2 [dB] shown in FIG. 11 with the temperaturerange of 20° C. to 40° C. (stores in the storage 40).

In this way, the electronic device 1 can perform the association for thetemperature range of 20° C. to 40° C. In this example, the electronicdevice 1 associates a frequency of 77.75 GHz as an optimum frequency inthe temperature range of 20° C. to 40° C. In addition, in thisdisclosure, the description of the signal intensity A [dB] to B [dB]with A and B as arbitrary numbers shall mean A [dB] or higher and lowerthan B [dB].

When the plurality of predetermined temperature ranges are respectivelyassociated in this way, the electronic device 1 can, for example, storethe correspondence in the storage 40, such as the table shown in FIG.12.

FIG. 12 is a diagram for showing an example of the association betweentemperature and frequency in the electronic device 1. In the exampledescribed above, as shown in FIG. 12, f3=79.75 [dB] is associated withthe temperature range 0 to 20 [° C.] as the optimum frequency. Further,in the example described above, as shown in FIG. 12, f4=77.75 [dB] isassociated with the temperature range 20 to 40 [° C.] as the optimumfrequency. Similarly, by performing the association shown in FIG. 9 foreach of the temperature ranges of −40° C. to −20° C., −20° C. to 0° C.40° C. to 60° C. 60° C. to 80° C., and 80° C. to 100° C. the informationin the table shown in FIG. 12 can be added. The information in the tableshown in FIG. 12 is filled, thereby the electronic device 1 candetermine the frequency of the transmitted wave T to be transmitted fromthe transmitting antenna 25 in a predetermined temperature range.

Thus, in an embodiment, the frequency of the transmitted wave T to betransmitted from the transmitting antenna 25 may be associated with thepredetermined temperature based on the result of receiving the reflectedwave R obtained by reflection of the transmitted wave T transmitted fromthe transmitting antenna 25, from the receiving antenna 31 at thepredetermined temperature. Here, in an embodiment, the frequency of thetransmitted wave T to be transmitted from the transmitting antenna 25may be associated with the predetermined temperature based on themultiple results of receiving each of the reflected waves R obtained byreflection of the plurality of transmitted waves T transmitted withdifferent frequencies from the transmitting antenna 31, from thereceiving antenna 25. Furthermore, in an embodiment, the frequency ofthe transmitted wave T to be transmitted from the transmitting antenna25 may be associated with the predetermined temperature based on theintensity of the received signal received as each of the reflected wavesR obtained by reflection of the plurality of transmitted waves T. Morespecifically, in an embodiment, the frequency of the transmitted wavewith highest intensity of the received signal received as the reflectedwave R among the plurality of transmitted waves T may be associated witha predetermined temperature as the frequency of the transmitted wave Tto be transmitted from the transmitting antenna 25.

Next, in the electronic device 1 according to an embodiment, anoperation of detecting a predetermined object based on the associationshown in FIG. 9 will be described.

FIG. 13 is a flowchart for explaining an operation of detecting apredetermined object by the electronic device 1 according to anembodiment. The operation shown in FIG. 13 may be started on theassumption that the association shown in FIG. 9 has been made for atleast some of the predetermined temperature ranges. Further, theoperation shown in FIG. 13 may be started when the electronic device 1detects the predetermined object 200 existing around the mobile object100.

When the operation shown in FIG. 13 is started, the controller 10 of theelectronic device 1 acquires the temperature detected by the temperaturedetector 60 (step S31). In step S31, the temperature detector 60 maydetect the temperature at the cover member 7 or in the vicinity of thecover member 7.

After acquiring the temperature in step S31, the controller 10determines the frequency based on the acquired temperature (step S32).Specifically, in step S32, the frequency selector 15 of the controller10 determines the frequency of the transmitted wave T to be transmittedfrom the transmitting antenna 25 based on the information stored in thestorage 40. Here, the storage 40 stores the association betweentemperature and frequency as shown in FIG. 12, for example. Therefore,for example, if the temperature detected by the temperature detector 60is 2° C., the frequency selector 15 selects the frequency f3=79.75 [GHz]corresponding to the temperature range 0 to 20 [° C.]. As a result, thefrequency determined in step S32 becomes 79.75 [GHz]. Further, forexample, if the temperature detected by the temperature detector 60 is38° C. the frequency selector 15 selects the frequency f4=77.75 [GHz]corresponding to the temperature range of 20 to 40 [° C.]. As a result,the frequency determined in step S32 becomes 77.75 [GHz]. Similarly, forexample, if the temperature detected by the temperature detector 60 is51° C. the frequency selector 15 selects the frequency f5 [GHz]corresponding to the temperature range of 40 to 60 [° C.].

When the frequency of the transmitted wave T is determined in step S32,the controller 10 controls the transmitting antenna 25 of thetransmitter 20 to transmit the chirp signal as the transmitted wave Twith the determined frequency (Step S33) Specifically, the controller 10instructs the signal generator 21 to generate the transmitted signal(chirp signal). The controller 10 then controls the chirp signal to betransmitted as a transmitted wave T from the transmitting antenna 25through the synthesizer 22, the phase controller 23, and the amplifier24. Here, the frequency selector 15 of the controller 10 notifies thesynthesizer 22 of the frequency determined in step S32. Then, thesynthesizer 32 raises the frequency of the signal generated by thesignal generator 21 to the frequency notified by the frequency selector15.

When the transmitted signal is transmitted as the transmitted wave T instep S33, for example, when the predetermined object 200 exists aroundthe mobile body 100, the transmitted wave T is reflected by the object200 and becomes the reflected wave R.

When the chirp signal is transmitted in step S33, the controller 10controls the receiving antenna 31 of the receiver 30 to receive thechirp signal as the reflected wave R (step S34). When the chirp signalis received in step S34, the controller 10 controls the receiver 30 togenerate a beat signal by multiplying the transmitted chirp signal andthe received chirp signal (step S35). Specifically, the controller 10controls the chirp signal received from the receiving antenna 31 to beamplified by the LNA 32 and multiplied with the transmitted chirp signalby the mixer 33. The process from step S33 to step S34 may be performed,for example, by employing a known millimeter wave FMCW radar technique.

When the beat signal is generated in step S35, the controller 10estimates the distance L to the predetermined object 200 based on eachgenerated chirp signal (step S36).

In step S36, the distance FFT processor 11 performs the distance FFTprocess on the beat signal generated in step S35. When the distance FFTprocess is performed in step S36, the signal intensity (electric power)corresponding to each frequency is obtained. In step S36, the distanceFFT processor 11 may perform the distance FFT process on the digitalbeat signal supplied from the AD converter 35. In step S36, the distanceFFT processor 11 may estimate the distance to the predetermined object200 based on determining whether among the generated beat signal, thepeak in the result obtained by performing the distance FFT process isequal to or higher than a predetermined threshold value. Further, thebeat signal on which the distance FFT process is performed in step S36may be a unit of one chirp signal (for example, c1 shown in FIG. 3), forexample.

After the distance is estimated in step S36, the controller 10 estimatesthe relative speed with the object 200 (step S37).

In step S37, the speed FFT processor 12 performs the speed FFT processon the result on which the distance FFT process has been performed instep S36. In step S37, the speed FFT processor 12 may perform the speedFFT process on the result on which the distance FFT process has beenperformed by the distance FFT processor 11. In step S37, the speed FFTprocessor 12 may estimate the relative speed with the predeterminedobject 200 based on determining whether the peak in the result obtainedby performing the speed FFT process is equal to or higher than apredetermined threshold value. The signal on which the speed FFT processis performed in step S37 may be a unit of chirp signals (for example, c1to c8 shown in FIG. 3) included in one subframe, for example.

After the distance is estimated in step S37, the controller 10 estimatesthe direction in which the reflected wave R arrives from the object 200(step S38).

In step S38, the arrival angle estimator 13 may estimate the directionin which the reflected wave R arrives from the object 200 based on theresult obtained by performing the speed FFT process in step S37. In stepS38, the arrival angle estimator 13 may estimate the direction in whichthe reflected wave R arrives by using an algorithm such as MUSIC andESPRIT as described above. The signal in which the arrival direction isestimated in step S38 may, for example, be a unit of all of the chirpsignals in 16 subframes (subframe 1 to subframe 16 shown in FIG. 3)included in one frame (for example, frame 1 shown in FIG. 3).

When the arrival direction is estimated in step S38, the controller 10detects the object 200 (step S39). In step S39, the object detector 14may determine whether the predetermined object 200 exists based on atleast any one of the distance estimated in step S36, the relative speedestimated in step S37, and the arrival direction estimated in step 38.The electronic device 1 according to an embodiment may perform theoperation shown in FIG. 13 for each frame, for example.

In this way, the controller 10 determines the frequency of thetransmitted wave T to be transmitted from the transmitting antenna 25based on, for example, the temperature detected by the temperaturedetector 60. Here, the temperature detector 60 may detect thetemperature at the cover member 7 or in the vicinity of the cover member7. That is, in an embodiment, the controller 10 may determine thefrequency of the transmitted wave T to be transmitted from thetransmitting antenna 25 based on the temperature at the cover member 7or in the vicinity of the cover member 7. Further, in an embodiment, thecontroller 10 may instruct to store the correspondence between thetemperature detected by the temperature detector 61) and the frequencyof the transmitted wave T to be transmitted from the transmittingantenna 25. In this case, a storage 40 configured to store thecorrespondence between the temperature detected by the temperaturedetector 60 and the frequency of the transmitted wave T to betransmitted from the transmitting antenna 25 may be provided.

In an embodiment, the correspondence between the temperature detected bythe temperature detector 60 and the frequency of the transmitted wave Tto be transmitted from the transmitting antenna 25 does not have to bestored in the storage 40 or the like. In this case, for example, anarithmetic expression or the like that defines the correspondencebetween the temperature detected by the temperature detector 60 and thefrequency of the transmitted wave T to be transmitted from thetransmitting antenna 25 may be stored in the storage 40 or the like. Inthis way, in an embodiment, the controller 10 may calculate thefrequency of the transmitted wave T to be transmitted from thetransmitting antenna 25 based on the temperature detected by thetemperature detector 60.

The radar sensors using conventional millimeter wave radar technique maynot be able to perform good measurements depending on the positionalrelationship with the transmitting antennas and/or the receivingantennas when the cover member such as the radar cover is made of resin,for example. For example, the transmitted signal and/or the receivedsignal passes through the cover member made of resin, which may cause aloss in the intensity of the received signal. It is assumed that thegreater the loss of the intensity of the received signal, the shorterthe distance that the radar sensor can detect the predetermined object.This is mainly due to the fact that the resin that makes up the covermember expands or contracts depending on the temperature, which changesthe loss of the intensity of the received signal when the transmittedsignal and/or the received signal pass through the resin.

On the other hand, the electronic device 1 according to an embodimentoperates so as to detect the temperature at the cover member 7 or theambient temperature and optimize the frequency of the transmitted wave Tat that temperature.

Therefore, the electronic device 1 can determine the optimum frequencyas the frequency of the transmitted wave T even when the temperature atthe cover member 7 or the ambient temperature changes. In this way, theelectronic device 1 can minimize the loss of the intensity of thereceived signal caused by the resin constituting the cover member 7,thus maximize the distance at which a predetermined object can bedetected.

Therefore, according to an embodiment of the electronic device 1, theperformance of detecting objects reflecting transmitted waves can beimproved.

The present disclosure has been described based on the drawings andexamples, but it should be noted that those skilled in the art will findit easy to make various variations or modifications based on the presentdisclosure. Therefore, it should be noted that these variations ormodifications are included in the scope of this disclosure. For example,the functions included in each functional part and the like can berearranged in a logically consistent manner. A plurality of functionalparts and the like may be combined or divided into one Each of theembodiments according to the present disclosure described above is notlimited to faithful implementation of each of the described embodiments,but may be implemented by combining or omitting some of the features asappropriate. That is, the contents of the present disclosure can besubjected to various variations and modifications based on the presentdisclosure by those skilled in the art. Therefore, these variations andmodifications are included in the scope of this disclosure. For example,in each embodiment, each functional part, each means, each step and thelike can be added to other embodiments in a logically consistent manner,or can be replaced with each functional part, each means, each step andthe like of other embodiments. Further, in each embodiment, theplurality of each functional part, each means, each step and the likecan be combined into one or divided. Each of the embodiments of thepresent disclosure described above is not limited to faithfulimplementation of each of the described embodiments, and may beimplemented by combining or omitting some of the features asappropriate.

The embodiment described above is not limited to implementation only asan electronic device 1. For example, the embodiment described above maybe implemented as a method for controlling devices such as theelectronic device 1. Furthermore, for example, the embodiments describedabove may be implemented as a control program for devices such as theelectronic device 1.

The electronic device 1 according to an embodiment may comprise at leasta part of only one of the sensors 5 or the controller 10, for example,as a minimum configuration. On the other hand, in addition to thecontroller 10, the electronic device 1 according to an embodiment may beconfigured to include at least any one of the signal generator 21,synthesizer 22, phase controller 23, amplifier 24, and transmittingantenna 25, as shown in FIG. 3, as appropriate. The electronic device 1according to an embodiment may also be configured to include at leastany one of the receiving antenna 31, LNA 32, mixer 33, IF part 34, andAD converter 35, as appropriate, in place of or together with thefunctional parts described above. Furthermore, the electronic device 1according to an embodiment may be configured to include a storage 40.Thus, the electronic device 1 according to an embodiment may beconfigured in various ways. When the electronic device 1 according to anembodiment is mounted on a mobile body 100, for example, at least anyone of the functional parts described above may be installed in asuitable location, such as inside the mobile body 100. On the otherhand, in an embodiment, for example, at least any one of thetransmitting antenna 25 and the receiving antenna 31 may be installedoutside the mobile body 100.

REFERENCE SIGNS LIST

-   -   1 Electronic device    -   5 Sensor    -   6 Sensor board    -   7 Cover member    -   10 Controller    -   11 Distance FFT processor    -   12 Speed FFT processor    -   13 Arrival angle estimator    -   14 Object detector    -   15 Frequency selector    -   20 Transmitter    -   21 Signal generator    -   22 Synthesizer    -   23 Phase controller    -   24 Amplifier    -   25 Transmitting antenna    -   30 Receiver    -   31 Receiving antenna    -   32 LNA    -   33 Mixer    -   34 IF part    -   35 AD converter    -   40 Storage    -   50 ECU    -   60 Temperature detector    -   100 Mobile body    -   200 Object (Body)

1. An electronic device, comprising: a transmitting antenna configuredto transmit transmitted waves; a receiving antenna configured to receivereflected waves obtained by reflection of the transmitted waves; and acontroller configured to detect an object reflecting the transmittedwaves based on transmitted signals transmitted as the transmitted wavesand received signals received as the reflected waves, wherein thecontroller determines frequencies of transmitted waves to be transmittedfrom the transmitting antenna based on temperature.
 2. The electronicdevice, according to claim 1, comprising a cover member configured tocover at least a part of at least one of the transmitting antenna andthe receiving antenna.
 3. The electronic device, according to claim 2,wherein at least a part of the cover member is made of resin.
 4. Theelectronic device, according to claim 2, wherein the controllerdetermines frequencies of transmitted waves to be transmitted from thetransmitting antenna based on temperature at the cover member or in avicinity of the cover member.
 5. The electronic device, according toclaim 1, wherein the controller instructs to store correspondencebetween the temperature and a frequency of a transmitted wave to betransmitted from the transmitting antenna.
 6. The electronic device,according to claim 1, comprising a storage configured to storecorrespondence between the temperature and a frequency of a transmittedwave to be transmitted from the transmitting antenna.
 7. The electronicdevice, according to claim 1, wherein the controller calculates afrequency of a transmitted wave to be transmitted from the transmittingantenna based on the temperature.
 8. The electronic device, according toclaim 1, wherein a frequency of a transmitted wave to be transmitted ata predetermined temperature from the transmitting antenna, based onresults of receiving a reflected wave, obtained by reflection of atransmitted wave transmitted from the transmitting antenna, from thereceiving antenna, is associated with the predetermined temperature. 9.The electronic device, according to claim 8, wherein a frequency of atransmitted wave to be transmitted from the transmitting antenna, basedon a plurality of results of receiving each of reflected waves, obtainedby reflection of a plurality of transmitted waves transmitted atdifferent frequencies from the transmitting antenna, from the receivingantenna, is associated with the predetermined temperature.
 10. Theelectronic device, according to claim 9, wherein a frequency of atransmitted wave to be transmitted from the transmitting antenna, basedon intensity of a received signal received as each of reflected wavesobtained by reflection of the plurality of transmitted waves, isassociated with the predetermined temperature.
 11. The electronicdevice, according to claim 10, wherein a frequency of a transmitted wavewith highest intensity of a received signal received as the reflectedwave among the plurality of transmitted waves is associated with thepredetermined temperature as a frequency of a transmitted wave to betransmitted from the transmitting antenna.
 12. A method for controllingelectronic device, including: a step of transmitting transmitted wavesfrom a transmitting antenna; a step of receiving reflected wavesobtained by reflection of the transmitted waves from a receivingantenna; a step of detecting an object reflecting the transmitted wavesbased on transmitted signals transmitted as the transmitted waves andreceived signals received as the reflected waves; and a step ofdetermining frequencies of transmitted waves to be transmitted from thetransmitting antenna based on temperature.
 13. A non-transitorycomputer-readable recording medium storing computer programinstructions, which when executed by a computer, cause the computer to:transmit transmitted waves from a transmitting antenna; receivereflected waves obtained by reflection of the transmitted waves from areceiving antenna; detect an object reflecting the transmitted wavesbased on transmitted signals transmitted as the transmitted waves andreceived signals received as the reflected waves; and determinefrequencies of transmitted waves to be transmitted from the transmittingantenna based on temperature.